Many surgical procedures require access to a target site within the human body where it is not possible to provide a straight passage. For example, obstructions created by the human anatomy and/or other surgical instruments being used for retraction of soft tissues or other purposes can prevent the availability of a straight passage. In such instances, it becomes difficult or impossible to use a straight instrument to access the target site.
Numerous devices have been developed in an attempt to address this problem. In one example, a drilling or screwing tool having a U-joint at the terminal end is used in conjunction with an instrument that guides the tip of the tool to the target site. This system is complicated because of the need for multiple instruments to carry out the drilling or screwing. In another example, crown gears are used at the end of the tool, but these crown gears tend to wear easily. Moreover, to keep the gear from slipping, a significant amount of force needs to be applied, which increases the wear and may fatigue the user of the device. In still another example, sleeves are used to guide a drilling or screwing tool to the target site, but these sleeves are typically large and bulbous.